Barely hours after Sebastian Vettel declared he was to leave Red Bull at the end of the season, the big-money numbers were being bandied around the Suzuka paddock with abandon. A figure of £50m has already been reported as the price Ferrari will have paid to lure the four-times world champion. But Formula One enjoys playing the numbers game and Vettel’s unexpected decision weighs heavy with forethought and the impression given is that it was not taken lightly and the lure of a bigger pay cheque played little part.

Yet the price tag for his services, as yet unconfirmed by either Vettel or Ferrari, has been brought up so quickly simply because the decision needs rationalising. Vettel won all his championships with Red Bull, a team that has monitored, cared for and provided him with the tools for such extraordinary success since he was spotted by the their adviser Helmut Marko when he was 12 years old. Their relationship has been especially close under team principal Christian Horner, who always took obvious pleasure in his drivers’ achievements and despite a difficult season this year, where he has struggled to come to terms with the new car and has been out-raced by his team-mate Daniel Ricciardo, there was nothing to suggest that the German would leave.

What’s more, he departs for a struggling Ferrari, who are severing their ties with Fernando Alonso. The Spaniard had joined the Scuderia in 2010 with the intent of adding to his two world championship titles. He leaves having managed only second at best and unhappy that rather than going forward the team look less likely now to present him with a title-winning car than they did four years ago. They are battling Williams for third place in the championship and should they lose that fight, it will be the first time since 1993 that Ferrari will have finished outside the top three.

It does not look like they will have much better to present to Vettel next year. The turmoil has not been confined to the track. Stefano Domenicali stood down as principal earlier in the year and chairman Luca di Montezemolo resigned last month. Ferrari sacked the designer of this year’s power unit, Luca Marmorini, in August. They have not won the title since Kimi Raikkonen pipped Lewis Hamilton in 2007.

This, even by the standards of Ferrari’s furious politicking and relentless demands for success, is not the ideal scenario for the arrival of an ambitious driver of Vettel’s calibre. If not for the money, then, what might be his motivation? The situation bears many similarities to Hamilton when he decided to leave McLaren in 2012. He too had grown up with the team, it was all he had known in Formula One and there was a distinct sense then that here was a young man who wanted to make a change.

For Vettel, too, that after all the time within the Red Bull bubble it is understandable he feels the need to take on a new challenge in a new environment. “It’s not a decision based on the current results, it’s more a voice inside me that kept growing and it’s a step that I’m very much looking forward to,” he said.

“You can compare it to at some point in your life you decide to grow up and move out of home. It is a big step like that – it feels like leaving home.”

There is also the timing. Vettel is 27 and will know from his experience in Formula One not to anticipate immediate success at Ferrari. He too will expect to have to build toward wins, which may take several years.

Alonso’s decision to leave is almost certainly what prompted Ferrari to come after him and offer the opportunity, as Horner acknowledges. “With Alonso extracting himself, it’s left a door open and Seb’s said to himself: ‘Do you know what? I fancy a go at that,’” he said.

And then there is Ferrari. There is nary a driver on the grid who would not relish a chance to drive the scarlet car. Back in 2010, Alonso said: “Driving a single-seater for the Prancing Horse is everybody’s dream in F1, and now I have the chance to make this dream come true.” He said on Saturday that he now feels fully in control of his destiny: “I have a very unique position,” the Spaniard said. “For so many years and with so much respectful work I have done on the track, I decide where to go, what I do and when I do it. Whatever I want to do I will do. I will race more or less in whatever place I want.”

Vettel, who grew up watching his fellow German Michael Schumacher take title after title for the Scuderia, doubtless feels the same lure of the most famous of all racing marques.

“There’s always been something at the back of his mind about Ferrari,” said Horner. “And the fact that Michael, who was his absolute idol, and all that heritage is a big pull on him.”

It was a dream Vettel had wanted to fulfil so badly that Horner felt powerless to resist. “The lure of Ferrari, his childhood idolising of Schumacher, the mystique of Ferrari and the timing was such an enormous draw that there was no point trying to convince him otherwise,” Horner added.

Vettel said in Suzuka: “There is the desire and hunger to create something new, and in the end that’s what made me decide to open another door.”

Yet while money does talk in F1 and the numbers always will matter, to explain away Vettel’s decision to such vulgarities seems to do a disservice to a driver long criticised for only winning because he was at the wheel of the fastest car. Clearly Vettel has chosen a new and very difficult challenge.